Paper machine felt dewatering method and apparatus



J. c. HINTERMAIER ET AL 3,313,679

A ril 11, 1967 PAPER MACHINE FELT DEWATERING METHOD AND APPARATUS 5Sheets-Sheet 1 Filed March 18, 1963 April 11, 1967 J. c. HINTERMAIER ETAL 3,313,679

PAPER MACHINE FELT DEWATERING METHOD AND APPARATUS 5 Sheets-Sheet 2Filed March 18, 1963 April 11, 1967 J. c. HINTERMAIER ET AL 3,313,679

PAPER MACHINE FELT DEWATERING METHOD AND APPARATUS 5 Sheets-Sheet 3Filed March 18, 1963 FIG.3

PIC-3.7.

Aprfl 11, 1967 J. c. HINTERMAIER ET AL 3333,6279

PAPER MACHINE FELT DEWATEHING METHOD AND APPARATUS 5 Sheets-Sheet 4Filed March 18, 1963 FIGII.

April 11, 1967 J. c. HINTERMAIER ET AL 3,313,679

PAPER MACHINE FELT DEWATERING METHOD AND APPARATUS 5 Sheets-Sheet 5Filed March 18, 1963 FEQQS.

United States Patent ()fi" 3,313,579 Patented Apr. 11, 1967 3,313,679PAPER MACHINE FELT DEWATERING METHOD AND APPARATUS John C. Hintermaier,Troy, and Dan E. Wicker, Londonville, N.Y., assignors to HuyckCorporation, Stamford,

Conn, a corporation of New York Filed Pvlar. 18, 1963, Ser. No. 265,8278 Claims. (Cl. 162199) This invention relates to an improved method andapparatus for dewatering the felts used in a paper machine, and it isparticularly concerned with the reduction of the Water content of suchfelts in the wet stages of the production of paper.

In forming a continuous web of paper from a pulp slurry, it is usuallyconsidered necessary to apply a relatively thick layer of the pulpslurry to a felt while the slurry still has a quite high water content.It may, for example, have a water content of 8090%, based on the wetWeight of the total mixture, at the time it is applied to the first feltin a series of felts normally used in a complete papermaking machine, inthe region that is in advance of the point at which the pulp attains thestatus of a self-sustaining sheet or Web. As will be appreciated,

the water content of the wet web of pulp or paper must be transferred tothe felt, in the early press sections of the machine, in order to bringthe consistency of the pulp mixture to the desired point, from thestandpoint of its water content, at which it may be advanced through thefinal drying stages to make the finished web of paper. As a result ofthe transfer of the water to the felt, particularly in the first presssection of the machine, the felt reaches a relatively high water contentin the course of its travel with the paper web, and it is then necessaryto remove a substantial part of the water from the felt before thelatter is again brought into position to receive another portion of thewater content of he pulp slurry which is delivered to it.

Various schemes have been suggested heretofore for the purpose ofremoving water from the felt in the course of its advance through aregion extending from the point where it leaves the paper web to thepoint at which it is again brought into the position where it receivesanother portion of the wet slurry. Such means have included pressrollers between which the felt, in the region mentioned, has beensubjected to a squeezing action to force out a certain part of its Watercontent. In some instances the press used for the purpose has beenprovided with suction means intended to speed up the removal of waterfrom the felt, and also prevent the objectionable accumulation of waterin advance of the nip of the press rollers which has been found to slowdown the permissible speed of operation of the machine and to produceobjectionable effects upon the web of paper being formed. However, thevarious expedients of this character which have heretofore been employedhave all been subject to certain objections. They have not made possibleany substantial increase in the overall speed of operation of themachine because they have failed to provide the necessary void volume inthe felt, as it is brought back into contact with another portion of theweb, to enable the felt to accept the necessary amount of water from theweb for the long sought high speed movement of the latter.

The various methods and means suggested heretofore have all led tocertain difficulties which have imposed a definite limitation upon thespeed of operation of the machine. One such difficulty has been theaccumulation of excess water at the ingoing side of the nip and this hasresulted in diluting of the sheet and crushing. This occurs atrelatively slow speeds of operation of the machine, whether the press isa plain press or is provided with a suction roll. The felt and Web atthe mid-point of a suction press are so compressed that the voids in thefelt are substantially completely filled, and even excess water may becarried into the nip to force the press rolls somewhat further apart.The degree of compression in most of the nip region is such as togreatly reduce the porosity of the felt and inhibit the passage of airtherethrough under the influence of the suction applied. Attempts havebeen made to overcome these difficulties by the employment of a blinddrilled bottom roll in the press or by the provision of a second band,which has sometimes been formed by weaving of metal wire, running insidethe felt. However, none of these schemes have made possible anysubstantial increase in the speed of operation of the machine withoutdamage to the paper web. Thus prior efforts to remove water rapidly fromthe paper and the felt have all resulted in objectionable marking of thepaper web due to high press roll loadings and the impossibility ofpreventing more than complete saturation of the felt as it is passed,together with the paper Web, through the regular press rollers of thepaper machine, with resulting disturbance of the matted relation of thepulp fibers forming the paper due to dislocations arising from therapidity with which water is caused to exist from the web, bothvertically and laterally on the upstream side of the lower press rollerof the machine. Plain presses which have been used up to the presenttime for squeezing water from the wet paper web or sheet into thesupporting felt have been found limited to a surface speed of movementof 800-1000 feet per minute in order to avoid difficulties of thecharacter mentioned. A higher speed of movement of the paper web hasbeen attained through the provision of a suction action at the press,but this has also been unduly limited and it has still left theobjectionable effect upon the formation of the desired paper sheet orweb when the speed of operation of the machine has been increased to adesired point. One difiiculty that has been noted in connection with theprovision of the suction means is that a very substantial percentage ofthe water drawn into the perforations of the roller to which suction isapplied will remain in those openings as they pass beyond the suctionbox and this water will then be thrown by centrifugal force outwardlyfrom the roller back to the felt.

A primary purpose of the present invention has been to provide anarrangement by which the felt, as it is brought into the region Where itreceives the paper Web from a Fourdrinier wire or the like, has a muchlower water content than has heretofore been permitted to remain. Thismakes possible the transfer of a higher percentage of water from thepaper web into the felt before the latter becomes saturated to the pointwhere water will flow backwardly around the lower press roller on theupstream side. The present invention has been found to make it possibleto operate the machine at a much higher overall speed without runninginto the difiiculties heretofore encountered through the development ofan excess quantity of water in the region of the nip of the press rolls.

To bring about the removal of a substantial percentage of the waterpicked up by the felt as it is squeezed, along with the paper web, inpassing through the regular press of the machine, the felt after beingseparated from the paper web on the downstream side of the press ispassed through one or more regions in which the water content of thefelt is expeditiously and greatly lowered without harmful efiects uponthe felt structure. For this purpose, the felt is passed through one ormore regions in which a blast of air under super-atmospheric pressure isforced through successive sections of the felt as these are beingcontinuously advanced. The arrangement is such that the air underpressure forcibly acts upon the water within the cavities of the feltstructure and upon the water coating the fibers and yarns and urges thiswater outwardly into a suitable receptacle or enclosure from which thewater may be continuously withdrawn. In one form of the invention thefelt is simply advanced continuously through one or more regions inwhich it is held by a sealing action against a device having a slot orseries of slots or perforations through which air under superatmosphericpressure may be blown through the felt. The opposite side of the slot,or series of slots or perforations, communicates with a receptacle whichmay be either at atmospheric pressure or at a sub-atmospheric pressure,the water and air mixture being continually discharged from thereceptacle. To produce the maximum purging action of the air so blownthrough the felt, it has been found highly desirable to have the air atsubstantially room temperature and not at an elevated temperature. Thehigher density of the air at the lower temperature will provide a moreeffective water purging action.

It has been found highly desirable, moreover, to effect the purging ofthe water from the felt by the passage of air under super-atmosphericpressure therethrough while the felt is simultaneously subjected tocompression to a substantial extent in the region in which the air isblown through it. For example, the felt may be passed through the nip oftwo perforated or slotted rollers which are rotated to impart aperipheral speed thereto commensurate with the desired speed ofoperation of the papermaking machine. Within the upper roller there isprovided a box which has a sealed relation to the inner wall of theroller, and which is completely enclosed except over the arcuate portionthat communicates with the slots or perforations in the roller. Airunder a desired pressure is constantly fed into this box, is then forcedthrough the slots or perforations, then through the felt in the nipregion of the rollers. The water thus purged from the felt is dischargedinto a similarly arranged box within the lower, slotted or perforatedroller. To avoid wastage of air and obtain the maximum benefits of theinvention most efficiently, it has been found desirable to confine thearcuate, open face of the box in the upper roller to the upstream sideof the latter, i.e., from the area in whcih the felt is first compressedto the line of maximum compression by the rollers, i.e., that region inwhich the felt is subjected to increasing compression. The arcuateextent of this nip region will vary with the thickness of the felt beingused, so that in any standard equipment of fixed construction the arethrough which the air is delivered to the felt should be limited to thatin which a felt of minimum thickness will be subjected to increasingcompression for the most economical use of air. On the downstream sideof the point of maximum compression of the felt the air will flow morefreely, because of the previous removal of water from the interstices ofthe felt. While this air will entrain and remove further moisture, itwill economize on air consumption if the box in the upper rollerterminates adjacent the line of maximum compression of the felt, anddoes not extend a substantial distance downstream from this line. Also,to purge water with a minimum consumption of air from felts of differenttypes of thicknesses that may be applied to a particular paper machine,it may be found desirable to construct one or both of the air deliveringand water receiving boxes within the squeeze rollers to enableadjustment thereof to extend over different arcs. However, this is notessential and the air delivery box and the air and water receiving boxmay be of fixed dimension and extend over equal arcs at opposite sidesof the nip. The water receiving box may advantageously be connected to apump capable of producing a sub-atmospheric pressure to further induce ahigh pressure differential across the felt and thus a superiorentrainment of water.

By an arrangement of the character described, a felt having a watercontent of say 60 to 75%, wet basis, as it approaches the nip of theslotted or perforated squeeze rollers, will be gradually compresseduntil the water con tent reaches substantial saturation, i.e., thecondition in which all of the interstices within the felt are filledwith water. By percent water content or moisture wet basis is meant theweight of the water in a specimen divided by the total weight of the wetspecimen times 100, as determined by the procedure described in ASTMStandards for Textile Materials, Tentative Metods for QuantitativeAnalysis of Textiles, ASTM designation D62959T, pages 317-8, 31st ed.,published November 1960. At the time indicated the air under pressureworks most effectively to force the water out of the interstices.Moreover, as the felt advances toward the line of maximum compression,the squeezing action upon the felt serves to cause the remaining waterto fill substantially all of the voids or interstices left within thesqueezed felt. It will be understood that the rate of advance of thefelt, the pressure of the air which produces the purging action and thediameters of the press or squeeze rolls may be so selected as to insuresubstantially filling of the interstices of the felt as the latter isadvanced throughout the region on the upstream side in which the felt isbeing subjected to increasing compression. This will make the purgingaction of the air efficient throughout the region specified. If thedelivery of air is limited to the upstream side of the maximumcompression line there will be no tendency of the air to blow freelythrough channels or passages in the felt that are not filled with water.However, as indicated above, the high velocity movement of air throughthe felt after the initial piston-like action of the air on thesubstantially saturated portions of the felt will further decrease thewater content, if the air under pressure is delivered to the felt in aregion downstream from the line of maximum compression of the felt.

Actually it is not necessary to compress the felt to the point that allof the interstices are filled with water. High speed and efficientpurging will take place if, at the time air under pressure is blownthrough the felt, the water in the felt forms a continuous, imperforatefilm or layer, so that there is no free air passage through the felt.For this purpose the extent of saturation of the felt may be less thancomplete as it is subjected to the-water purging action of air underpressure.

In the practice of the invention it is important to provide effectivesealing means on all sides of the region in which the air is being blownthrough the felt, so that the escape of air under pressure in lateraldirections, rather than through the felt, will be held to a minimum.This not only conserves the air being used but also prevents spatteringof water in directions in which it may do harm.

Other special features of the invention will become apparent as certainspecific embodiments of the same are discussed in further detail.

With the foregoing and other purposes of the invention in view, variousmeans and methods of putting into effect the advantageous features abovementioned will now be described in further detail in reference to theaccompanying drawings in which:

FIG. 1 is a schematic view showing one arrangement for purging waterfrom a felt by air under superatmospheric pressure; the means providedfor this purpose is shown in relation to conventional press rolls of apapermaking machine;

FIG. 2 is a perspective view showing schematically a modifiedarrangement for applying air under pressure to a wet felt for dewateringthe latter;

FIG. 2A is a schematic viewing showing, in elevation, the relationshipof various parts involved in the arrangement of FIG. 2;

FIGS. 3, 4, 5, 6, 7, 8, 9 and 10 are perspective views showing detailsof various arrangements for providing an effective seal against loss ofthe water purging air;

FIG. 11 is an elevational view, partly in vertical section, showing astill further form of apparatus which may be employed in carrying outthe invention;

FIG. 12 is a perspective view illustrating a sealing arrangement whichmay be incorporated in the construction of FIG. 11;

FIG. 13 is a schematic view of yet another form of apparatus which maybe employed to effect water purging of felts by air under pressure;

FIG. 14 is a detail view showing in cross-section one of the cylindersemployed in the FIG. 13 embodiment of the invention; and

FIG. 15 is an elevational view, partly in vertical section, showingstill another embodiment of the invention.

Referring now to FIG. 1, this shows a web of paper being delivered fromany suitable part of a conventional papermaking machine, such as theFourdrinier wire or the couch rolls of such a machine, to a felt 11. Thelatter may be of any conventional form and will be of the characterfound preferable for the removal of water from the paper web, dependingupon the type of paper being produced. The web 10 and the felt 11 areadvanced at a quite rapid rate in the direction indicated by the arrowand they are passed through the nip of presser rolls 12 and 13. Thesemay be of the irnperforate type adapted to impart simply a squeezingaction to the paper web and felt as they pass through the nip. However,if desired, the lower presser roll 13 may be a perforated cylinder orone that is otherwise provided with suitable passages through the wallthereof, and there may then be provided in the region of the nip of thepress a suction box within the roll 13 to assist in the removal of thewater being squeezed out of the paper. Such suction means and theprovision of perforations in the roll 13 are not required however if thefelt is reduced to the state of dryness preferably provided inaccordance with the invention, i.e. with a water content of between 10%and 40%, wet basis, since the water squeezed from the paper will thennot completely saturate the felt even in its compressed state betweenthe rollers 12 and 13.

After the paper web and felt have passed through the nip of the pressrolls, the paper Web may be picked up in the conventional manner anddelivered to a subsequent portion of the papermaking machine, such asanother stage of the drying section. The felt will be passed aroundsuitable rollers 14 and 15 and then delivered to a first stage of thewater purging means contemplated by the present invention. This means,as shown, may include a drum or cylinder 16 which is held stationary, Itis provided at one end with an opening 16a for the introduction of airunder a suitable pressure, and its periphery is provided with a slot1612 which extends substantially across the width of the felt. Thelatter is held upwardly against the drum 16 in the region of the slot1611 by means of cylinders or rods 17 and 18. These cylinders or rodsare adapted to retain the felt firmly against the outer periphery of thedrum 16 at each side of the slot Nb and thus provide an effective sealin the region of the passage 16b through which the air under pressure isbeing blown. Suitable sealing means may also be provided adjacent theside edges of the felt to eliminate any tendency of the air underpressure to escape in the lateral direction. Such edge sealing means maybe of the same general character as the cylinders or bars 17 and 18. Allof these sealing means may be formed of a material which is wearresistant and which at the same time will not wear out the surface ofthe felt as the latter is being passed at high speed through the purgingregion. Suitable materials for this purpose are synthetic plastics, suchas Teflon (which is a polymer of tetrafluoro ethylene) and Rulan (whichis a polyethylene resin).

It will be noted that the surface of the felt which is supporting thepaper web at the nip of the presser rolls 12 and 13 will be at theunderside of the passage between drum 16 and cylinders 17 and 18. Thisis desirable, since any impurities or particles picked up from the paperweb at the press rolls will then be expelled downwardly into a suitablereceptacle 19 as the air under pressure within the drum 16 forces thewater with a piston-lik action from the felt. The receptacle 19 isprovided with an opening 20 in its bottom which may be connected withany suitable delivery system for disposing of the water and impuritiespurged from the felt.

After being subjected to the water purging action of the air underpressure in drum 16 the felt will be advanced around a pair of rollersor cylinders 21 and 22 and then through a second water purgingarrangement similar to that described. This second arrangement mayinclude a drum 23 having an inlet 23a for the introduction of air underpressure and a slot 23b for discharge of air under pressure through thefelt as the latter is held firmly against the drum 23 by cylinders orrods 23c and 23d and by edge sealing members of the character describedabove. After passing beneath the drum 23, the felt is then passed aroundrollers 22a and 22b and brought back into engagement with anotherportion of the paper web. In its passage beneath the slot 23b, the feltwill be in inverted relation to that which it passed through the firstpurging means described. This tends to insure a more complete drying ofthe upper surface of the felt as the water within its passages orinterstices is blown into a receptacle 24 from which it is led throughan outlet 24a to any desired point of disposal.

The width of the slots 16b and 23b, in the direction of movement of thefelt may be of any suitable dimension. These slots should be wide enoughto insure an adequate time for the air under pressure to force asubstantial amount of water out of the passage through the felt, by apiston-like action, as successive sections of the felt pass across theslots. In some instances it may be found desirable to have a number ofpurging units 16 arranged to operate upon the felt successively, andalso a number of purging units 23 similarly arranged to operatesuccessively on the felt in the second stage of the dewateringoperation.

In some instances, where the speed at which the felt must be advanced isquite high, in order to keep up with a high speed operation of the papermachine, it may be found desirable to support the felt by a strongporous fabric or wire belt in the regions of the purging units 16 and23. This will permit the provision of circumferentially wide openings16b and 23b, which may suitably be subdivided by partitions into anumber of sections, and will also permit the use of air under relativelyhigh pressures. Two such belts are indicated schematically at 25 and 26in FIG. 1. They will assist in holding the felt firmly against the drums16 and 23 in the regions of the slots 16b and 23b, and thus preventbulging which might occur if the slots are of substantial width and theair pressure is hi h. Also they assist in maintaining the desiredeffective seal around the air delivering slots. As shown in FIG. 1, thebelt 25 is supported by rollers 25a, 25b, 25c and 250, one of which maybe driven to cause the upper course of the belt to travel in the samedirection and at the same speed as the cooperating portion of the felt.By applying an appropriate tension to the belt, and with the aid of thecylinders or rods 17 and 18, a certain squeezing action may be impartedto the felt in the region of the opening 16b. The belt 26 may besupported by rollers 22, 26a, 26b and 26c, and it may be driven andtensioned in the same manner as belt 25. In lieu of this arrangement thebelt 26 may be caused to follow the felt 11 around the rollers 22a and22b, then through the nip of the press rolls, around roller 14, and thento roller 26c, whose location may be shifted slightly to avoid contactof the downwardly extending portion of belt 26 with the lower portion ofroll 13. This arrangement has the advantage of enabling water to besqueezed from the felt into the supporting belt as they pass through thenip of the press rolls. Then as the felt and the belt 26 pass beneaththe drum 23 the water is purged from both the felt and belt.

In the use of the term felt herein, it should be understood as referringto belts formed of any of the materials conventionally employed in theproduction of felts or fabrics used for conveying the wet paper webthrough the press rolls of the paper machine.

To bring about the removal of a substantial amount of water from thefelt by the air purging action, it has been found desirable to subjectthe felt to the action of the air for a substantial fraction of asecond. This is in order to achieve an important purpose of theinvention, namely the reduction of the water content of the felt tobetween 10% and 40%, wet basis, i.e., of its wet weight, beforesuccessive portions are again brought into engagement with the wet paperWeb. The following table indicates the results obtained in connectionwith a number of different types of felts within 0.5 second purgingtime, with certain felts subjected to 25% compression and the otherfelts subjected. to 30% compression and also with all of the feltssubjected to 50% compression at the time of the purging action.

30% COMPRESSION-0.5 SEC. PURGING TIME Design 126 95 207 30 176 269Initial Moisture (percent) .3 59.7 62. 4 64. 65. 4 62.9 Percent Moistureloss 7 14. 0 *9. 7 11. 6 11. 3 *11. 9 No. of samples tested 3 3 4 4 350% GOMPRESSION0.5 SEC. PURGING TIME Initial moisture (percent) 59. 358. G 61.4 64. 8 65 4 62.2 Percent Moisture loss 2 .4 18. 6 16. 4 13. 65 21. 2 N0. of samples tested 4 3 3 3 3 2 Compression.

In a similar manner, the following table shows the effect of a 0.25second purging time during which air under pressure is forced throughthe felts with the latter compressed firstly to 25 or compression andthen to compression.

30% COMPRESSION-0.25 SEC. PURGING TIME *25% Compression.

Still another test applied to a felt designated 259, with air blownthrough it while the felt was under 50% compression for the fractions ofa second indicated in the table below, shows that substantial amounts ofwater were removed within 0.17 second.

Felt compression 50% The various felts involved in the tests reported inthe foregoing tables were of the following types:

C. F. Wet 126.Common Fou-rdrinier press felt; reverse broken twillweave, weighing 3.5 ounces per square foot. The design containsapproximately 25% nylon, wool; it is frequently used in makingnewsprint.

Common Wet 259, 269.Used on cylinder machines making a wide range of boxboard and cardboard; 4 harness satin weave. Felts weigh approximately2.8

ounces per square foot, 100% wool. The #269 is a lighter, thinnerversion of #259. It weighs about 2.2 ounces per square foot.

S. F. Press 176.A fine press felt, duplex, plain plus satin weave, 2.6ounces per square foot. The filling yarns contain 25% nylon; warp is100% wool. It is used on a wide variety of Fourdrinier first presses.

Plate .--A very fine press felt, modified satin weave, wool;approximately 3.0 ounces per square foot. It is used on a wide varietyof second and third press positions making smooth finish papers.

Super Plate 30.Like #95 but thinner and capable of producing muchsmoother paper, 2.6 ounces per square foot, 100% Wool.

Pulp 207.A coarse, plain weave felt, 25 nylon, 75 wool, weighing about 3ounces per square foot. Used in making coarse grades of roofing paperand in extracting water from pulp sheets.

By preparing graphs from the data provided in the foregoing tables, itappears clear that a very substantial amount of water may be purged froma wet felt by forcing air under pressure through the felt during asmaller fraction of a second than specifically indicate-d in the tables.It appears that onetenth of a second, or even somewhat less, is adequatetime for the purging of a quite substantial amount of water from a wetfelt, particularly when the felt is in a compressed condition at thetime the air is blown through it. However, to achieve the extent ofreduction of water content of the felt desired for the primary purposeof the present invention, it seems necessary to subject the felt to theair purging action for at least 0.08 of a second if the felt is notbeing compressed substantially at the time the air is being blownthrough it. In general, it may be stated that a greater amount of timeis required when the felt is not compressed at the time the air is blownthrough it. Some improvement in the extent of water removal by the airunder pressure is produced by increasing the extent of compression ofthe felt, but the increase in the rate of water removal after the felthas been compressed to the extent of 50% of its normal thickness hardlywarrants higher compression. Thus, compression to the extent of between30 and 50% is considered to be best for the purposes of the invention.

The speed of removal of a desired percentage of water from a feltdepends to a substantial extent upon the pressure maintained on the airthat is blown through the felt. In the tests reported in the foregoingtables the air was withdrawn from a tank having an initial pressure of30 lbs/sq. inch. At the end of 0.5 sec. purging the pressure had droppedto 16.5 lbs., while at the end of the 0.25 sec. purging the pressure haddropped to between 21 and 22 lbs. Of course in the regular commercialuse of the invention the air supply system will be such as to maintain asubstantially uniform pressure of the desired amount. But other testdata indicates that to achieve a substantial reduction in the moisturecontent of the felt within a brief time interval of less than 0.5 secondit is desirable to employ air under a pressure of at least 8 p.s.i.above atmospheric. The preferred pressure is in the range between 10 and40 p.s.i. above atmospheric, but higher pressures, up to 100 p.s.i., maybe used provided the felt is of such character and is so supported atthe time the air is blown through it, that no harm will be done to thefelt by the high pressure air.

Referring now to FIGS. 2 and 2A, there is shown in schematically anotherform of apparatus which may be used for the air purging of water fromwet felts. 'I -he felt is indicated at 27 and it is passed around aroller 28, which may be the lower roller of one of the press roll unitsof a paper machine, corresponding with roller 13 of FIG. 1. From thispoint the felt is passed around a roller 29 which may suitably besupported for movement in the direction indicated by the arrows to applythe desired amount of tension to the felt. It then passes around rollers30 and 31 back to the press roll 28. The felt may be advanced by a beltconnection 32 from a pulley on the output shaft of a variable drivemechanism 33 to a pulley connected with roller 31. Drive mechanism 33may include an electric motor and suitable reduction gearing. In theirmovement from roller 30 to roller 31 the successive portions of the feltpass beneath a hood 34 into which air under a desired pressure may beblown through a line 35 and an opening 36 in the hood into the interiorof the latter. The bottom of the hood is provided with transverselyextending partition members 37 to form a plurality of passages 38 forthe discharge of the air under pressure through the felt. As will beexplained in greater detail hereinafter, suitable provision is made foran effective seal between all sides of the lower edge of the hood andthe surface of the felt to prevent any substantial escape of airlaterally from the hood without passing through the felt.

Beneath the felt, in vertical alinement with the hood 34, is areceptable 39 which is preferably arranged for vertical adjustment intoand out of engagement with the undersurface of the felt. In moving thereceptacle upwardly, it may be urged under a suitable pressure againstthe felt so as to exert a squeezing action upon the latter to compressthe felt to a desired extent. Receptacle 39 may be provided withtransversely extending partitions alined with partitions 37 of the hoodto make possible the squeezing and compressing action on the feltthroughout a portion of the length of the hood. The 'lower ends of thepartitions 37 and the upper ends of similar partitions in the receptacle39 are preferably provided with a layer of a low friction producing andgood wear resistant material, such as Teflon or Rulan. In lieu of thispartitioning of the receptacle it may, however, be provided with aplurality of rollers 40 adapted to retain and guide a belt 41 formed offabric or wire, or the like. This belt, which may be similar to thebelts 25 and 26 of FIG. 1, is additionally supported by rollers 42, 43,45, 46, 47 and 48. It may be driven at the same speed as the felt by asuitable connection from the drive means 33 through a belt 49 connectedwith a pulley carried by the roller 45. The roller 46 is preferablyarranged for movement in the direction of the arrows showin in FIG. 2Ato apply a suitable tension to the belt 41 and to enable the uppercourse of the belt to be lifted and lowered in relation to the hood 34.Water and impurities purged from the felt and forced through the belt 41into the receptacle 39 may be removed from the latter along with the airthrough an outlet 50.

An advantage of the foregoing construction schematically illustrated inFIG. 2A, with or without a supporting, abrasion-resistant "belt 41, isthat it makes possible the exposure of the felt to the air underpressure for a longer period of time than is reasonably possible in asingle purging arrangement of the type shown at 16 and 23 in FIG. 1.Also it enables a somewhat greater compression to be applied to the feltin the region of the hood 34 and receptacle 39, by virtue of the liftingforce adapted to be applied to the receptacle 39 and the belt 41 to urgethe latter or the transverse partitions in the receptacle, against theundersurface of the felt. I

In some cases it may be found that the simultaneous purging of waterfrom the felt and a supporting fabric will not remove the water from thesupporting fabric as fully as desired, so as to enable this to assist incarrying away the water discharged from the felt in the specifiedpurging step. To insure substantially complete removal of Water from thesupporting fabric it may be found desirable to subject this to aseparate purging action. Thus, as shown in FIG. 2A, air-jet supplyingmeans may be provided to more fully remove the water from the supportingfabric itself and thus improve the effectiveness of the air purgingaction on the felt in its next pass beneath the hood 34. Any suitableform of air-jet producing means may be provided across a portion of thesupporting fabric 41 after it has passed, along with the felt, throughthe combined air purging region of hood 34. For example, there may beprovided an elongated tubular member 50a extending across the width ofthe supporting fabric, this tubular member having an inlet 5% for theintroduction of air under substantial pressure, and outlet means 500adapted to discharge jets of air through the supporting fabric. Thisoutlet means may be in the form of a single narrow slot or in the formof a number of closely spaced passages of relatively small crosssectional area. The air discharged through the outlet means Stlc removesa substantial part of the water remaining in the supporting fabric anddelivers this into a receptacle 50d from which it may be discharged,along with the air, through an outlet 5% to any suitable point fordisposition.

Since the purging effected by the air-jets discharged from members 560is achieved by the high velocity movement of the air through the fabric,it is unnecessary to provide sealing means in this region. There islittle or no tendency of the air to be deflected laterally along thesurface of the supporting fabric.

It will be understood that a variety of other forms of high velocity,air-jet producing devices may be used, in lieu of the form schematicallyshown in FIG. 2A. Also it will be understood that similar means forseparately removing water by means of air-jets from a supporting fabricmay be employed in connection with other embodiments of this inventioninvolving the use of a supporting fabric for the felt in the region inwhich it is subjected to the air purging action, such as that describedin connection with FIG. 1 and that to be described in connection withFIG. 11.

Means of removing water from the supporting fabric, other than theair-jets mentioned above, may be employed effectively. These include theapplication of suction by suction boxes; the use of wipers or wiperblades; the use of scraper blades or deflectors that rest against thesurface of the moving porous supporting fabric disposed at an acuteangle to the direction of travel so that water is withdrawn anddeflected from the pores, as commonly practiced on the moving wireforming screens of paper machines; blasting with steam; throwing freefrom the pores by centrifugal force; transfer from the pores to thesurface of a rotating roll or drum with which the porous fabric runs incontact, and removal from such surface by scraping or wiping blades.

Referring now to FIGS. 2-10 inclusive, there is disclosed schematicallyvarious arrangements for providing an effective seal along all of theedges of the hood 34. For example, as shown in FIGS. 2 and 3, the sealalong the longitudinal edges of the hood may be provided by a pair ofcontinuously moving bands 51 and 52. These bands may be of circularcross-section, as shown in FIG. 3, but they may be of othercross-sections, as shown in certain of the other figures. The band 51which effects the seal along the forward longitudinal edge of the hood34, as seen in FIG. 2, may be trained around a series of pulleys 51a,51b, 51c and 51d. This band may be advanced through its frictionalengagement with the felt 27 or the supporting fabric 41, or it may beindependently driven at the same speed of advance as the supportingfabric and the felt by suitable connections from the drive means 33. Therun of this band advancing between the pulleys 51c and 51d will pressagainst the edge portion of the supporting fabric or of the felt under asufficient force to effect a good seal. Belt 52 is similarly trainedaround a series of pulleys 52a, 52b, 52c, 52d, 52a and 52 which arepositioned below the portion of the felt and the sup porting fabric thatis traveling toward the left (FIG. 2) beneath the hood. Pulleys 52b, 52cand 52d may suitably be carried or formed at the ends of the rollers 40of FIG. 2A, or they may be journaled upon trunnions extending from theends of non-rotatable members formed of bar stock, pipe stock or rodssecured to the upper portions of the side walls of receptacle 39 in thepositions shown for rollers 40 in FIG. 2A. In the latter event, thesenonrotatable members should be formed of, or should be provided with athick layer or coating in the regions which engage the belt 41 that iswear resistant and presents a low frictional resistance to the movementof the belt 41 thereacross. The belt 52 is urged upwardly against theedge portion of the supporting fabric with a suitable force to providean effective seal. It may either be driven through its frictionalengagement with the supporting fabric, or it may be independently drivenby a suitable connection from the drive 33 to one or another of thesupporting pulleys. At the opposite, or rear side of the hood 34,similar sealing belts may be provided to cooperate with the adjacentedge portion of the felt or the supporting fabric. This is indicated inpart in FIG. 2 by the showing of the belt 51 which is supported andguided by pulleys 510, 51'b, 51's and another pulley (not shown) alinedwith the pulley 510'. It will be understood that a belt corresponding tobelt 52 will be provided for cooperation with the belt 51' at the rearside of the hood, so that the longitudinal edge of the supporting fabricis gripped between the two belts.

For providing an effective seal along the right end of the hood 34 (FIG.2) a stationary bar 53 (FIG. 3), which may suitably be rectangular incross-section, is mounted in a channel member 54. The arrangement issuch that the bar 53 is held in engagement with the upper surface of thefelt 27 completely along the right end of the hood from a point adjacentthe path of travel of the belt 51 to a point adjacent the path of travelof the belt 51'. Bar 53 is preferably formed of a wear resistant and lowfriction creating material such as Teflon or Rulan. A similar bararranged in a similar manner across the left end of the hood serves toeffect a good seal at that end, between the lower edge of the hood andthe upper surface of the felt. Thus it will be seen that the entire areathrough which air is blown from the hood 34 through the felt and thesupporting fabric will be sealed along its four edges to prevent lateralescape of the air. As shown in FIGS. 4 and 5, the transversely extendingbar may have a trapezoidal cross-section, as shown at 53' and theretaining channel member may have a similar crosssection, as shown at54.

In lieu of the traveling belts 51 and 52, there may be providedstationary sealing means along the forward and rearward, longitudinaledges of the bottom of the hood. Thus, as shown in FIG. 6, there may beprovided two angle members 55 and 56 which extend throughout the lengthof the hood. One or another of these members may suitably be arrangedfor vertical adjustment to facilitate the introduction of the felt andits supporting fabric between them. Member 55 has a downward projection55a, preferably of semi-circular cross-section, adapted to urge the edgeportion of the supporting fabric 41 into a depression 56m in the anglemember 56. The engagement of the edge portion of the supporting fabricby projection 55a will be such as to urge it lightly into the depression561: without causing any substantial resistance to movement of thesupporting fabric, but at the same time to provide a quite effectiveseal against the lateral escape of air. Angle members 55 and 56 arepreferably formed of or coated with a good wear resistant and lowfriction producing material, such as Teflon, Rulan, or the like. It willbe understood that a similar arrangement can then be provided along therearward longitudinal edge of the hood.

FIG. 7 discloses a further embodiment of suitable means for effecting agood seal along the longitudinal edges of the hood. It is similar to thearrangement shown in FIG. 3 but provides a longitudinally extendingmember 57 above the course of the felt which passes beneath the hood.This member 57 is so constructed as to provide a guide groove 57a ofsemi-annular form through which the lower course of the belt 51 mayfreely travel. This serves to insure firm engagement of the lower courseof belt 51 which the upper surface of the felt or, if desired, merelythe upper surface of the supporting fabric 41. A similar guide membermay be provided below the supporting fabric 41 to insure properretention of the hori- Zontal course of the belt 52 against theundersurface of the edge portion of the supporting fabric. FIG. 8discloses an arrangement similar to that shown in FIG. 7 but involves achannel member 57' arranged to receive and guide the upper course of asealing belt 51" of rectangular cross-section. The lower belt 52",arranged in the manner of belt 52 in FIG. 2, is also of rectangularcross-section, and the two belts will then preferably cooperate withonly the edge portion of the supporting fabric 41. Belt 52", at itsforward end, passes around the pulley 52"a, and it will be understoodthat belt 51" passes around a similar pulley located in the positionindicated for pulley 510 of FIG. 2. If desired, another channel membersimilar to member 57', but in inverted relation, may be provided forretention of the lower belt 52" against the lower surface of thesupporting fabric throughout the length of the hood. In connection withthe FIG. 7 and FIG. 8 arrangements it will be understood thatcorresponding belts will be provided along the rearward edge of thehood.

Still another form of sealing means is disclosed in MG. 9. Thiscomprises channel member 58 extending longitudinally of the hoodadjacent its forward side and arranged to receive a sealing bar 59 ofrectangular crosssection. Similarly, an angle member 60 disposed alongthe forward edge of the hood 34 is adapted to retain a lower sealing bar61. Bar 59 is urged downwardly into engagement with the upper surface ofthe edge portion of the supporting fabric 41 by a number of springs 62disposed within the channel of member 58. In the same manner, the bar 61is urged upwardly under a suitable force into engagement with the lowersurface of the supporting fabric by a series of springs 63 disposed inthe channel of member 60. It will be understood that the bars 59 and 61are formed of a good wear resistant and low friction producing material.

A further embodiment of the invention is schematically disclosed in FIG.10. In this form, the felt 27 may have the supporting fabric 41 beneaththe felt in the region in which it is being subjected to the purgingaction, and it may also have a similar fabric 41a applied to its uppersurface in this portion of its run. Any suitable arrangement of pulleysmay be provided for carrying and directing the upper fabric 41a, andconnections from the drive unit 33 may be provided for advancing it atthe same speed as the felt. Sealing along the longitudinal edges of thehood 34 may be effected by the provision of angle members 64 and 65disposed respectively above the upper surface of fabric 41a and belowthe undersurface of the fabric 41. These angle members extend throughoutthe length of the air discharge opening in the hood and are preferablyformed of wear resitsant and low friction producing materials. The anglemembers at each side of the advancing supporting fabrics and felt arepreferably so mounted in relation to the hood as to be shiftablevertically in relation to each other, so as to facilitate their assemblyin proper relation to the felt and supporting fabrics and to cause themto urge the longitudinal edges of the two supporting fabrics togetherwith a force sufficient to insure an effective seal. Any of the meansheretofore described may be provided for sealing the two ends of thehood which extend transversely of the direction of movement of the feltand supporting fabrics. Of course any of the other means suggestedherein for sealing the longitudinal edges of the hood in relation to theedge portions of the felt and supporting fabric may be used in lieu ofthe angle members 64 and 65. The advantage of employing the two fabrics41 and 41a at opposite sur- 13 faces of the felt 27 is that it makespossible a suitable compression of the felt without subjecting the feltto wear producing friction forces.

It will be understood that any of the schemes described above inrelation to the FIG. 2 embodiment of the invention, for providing aneffective seal along the edges of the opening through which air is blownthrough the fabric may be adapted for use in connection with theembodiment of the invention disclosed in FIG. 1. Also it should beunderstood that belts or bars used in effecting proper sealing may be ofany appropriate cross-section, such as those described above whetherused longitudinally or transversely of the direction of movement of thefelt.

FIGS. 11 and 12 disclosed another form of apparatus which may beemployed for the purging of water from felts. In this embodiment of theinvention the felt 27 is delivered to and passed partially around aroller 66 and is then passed around a large, hollow, perforated drum 67.The perforations through the wall of this drum are indicatedschematically at 67a in FIG. 11. It will be understood that theseperforations are distributed completely around the circumference of thedrum and in a direction longitudinally of the drum. After passing almostcompletely around the drum the felt is carried through a suitable arearound a small roller 68 from which it is delivered to a suitable pointfor reception of the paper web. An outer shell 69 almost completelysurrounds the drum 67 and completely encloses the ends of the drum 67.In the circumferential direction around the drum 67, the portion of theroller 68 over which the felt is carried, is positioned at a pointclosely adjacent the corresponding portion of the roll 66. Close to theexit side of the nip between roller 66 and drum 67, the outer shell isprovided with a sealing arrangement 69a, which may suitably be in theform of a channel member retaining a bar of wear resistant and lowfriction producing material, this bar extending throughout the length ofthe drum 67 which is engaged by the felt. Similarly, at the oppositeside, the outer shell is provided with a sealing means 6% closelyadjacent theroller 68. Air is introduced into the drum 67 through aninlet 6717 under a suitable pressure and is blown outwardly through theopenings 67a in the drum and through the felt to .force water out of theinterstices of the felt into the space between the shell and the outercasing 69. The water and moisture retaining air which thus collectswithin the cas ing is withdrawn from the latter through outlet 690, thatmay suitably be connected to a vacuum or suction producing device. Inthe region between the' rollers 66 and 68 there is provided a segment 70mounted in good sealing relation to the drum 67, by any of the meansheretofore described, adapted to prevent the discharge of anysubstantial amount of air into the atmosphere through the openings 67ain the drum, as the felt approaches and passes beyond the arc covered bythe member 70.

To retain the felt 27 firmly against the outer surface of the drum 67and to apply a certain compressive force to the felt, there ispreferably employed a supporting fabric 41 which passes around theroller 66 beneath the felt 27 and then becomes disposed outwardly of thefelt 27 in the passage of the latter around the drum 67. The means forrotating the drum 67 from a driving unit, such as 33 in FIG, 2A, willserve to impart the desired movement to the felt 27 and the supportingfabric 41. Any suitable tensioning means may be applied to thesupporting fabric to cause it to impart a squeezing action to the feltas the latter passes around the drum 67.

FIG. 12 shows an arrangement which may suitably be employed for sealingthe edges of the felt and supporting fabric in the circumferentialdirection around the drum 67. This means may comprise a substantiallyannular channel member 71 carrying a substantially annular element 72formed of suitable wear resistant and low friction producing material.Element 72 is shown as being rectangular in cross-section, but it may beof circular or trapezoidal or other cross-section. Sealing means of thischaracter should be provided at both ends of the drum 67. The elements71 and 72 may be secured to the outer casing 69 and should becoextensive with the latter. If desired, they may be positionedoutwardly of the ends of the rollers 66 and 68 and the shield 70 as Wellas the longitudinally extending sealing members 69a and 6911. In thisevent they may extend at one end up to the plane which passes throughthe axes of the roller 66 and drum 67, and at their other ends to theplane which passes through the axes of the roller 68 and drum 67.

Turning now to FIG. 13, there is shown another embodiment of theinvention which, like that shown in FIGS. 11 and 12, provides for asubstantial purging time even for a felt that is advancing at the raterequired for a very high speed operation of the paper machine. In thisembodiment, there is provided a large tank 73, which may be ofrectangular cross-section both vertically and horizontally and which isadapted to receive air at a suitable rate and under a suitable pressurethrough an inlet 73a. The felt 27 to be purged is introduced into thetank through an opening 74 which is provided with sealing rollers orrods75 to prevent the escape of any substantial amount of air through theopening 74. Felt 27 is than led successively around a number ofperforated cylinders or drums 76 within the tank. After its passagearound the successive drums or cylinders the felt is passed outwardlyfrom the tank through an opening 77 provided with sealing rollers orrods 77a. As is shown in FIG. 14, each of the cylinders or drums 76 isprovided with a large number of slots or perforations through itsperiphery throughout its length and around its circumference. The airunder pressure within the tank 73 will pass through the felt into theinterior of the cylinders or drums 76. In those regions of the drumswhich are not surrounded by the felt, there is provided a shell 78mounted in sealing relation to the periphery of each of the drums so asto prevent free movement of air into the drums without passing throughthe felt. The drums 76 are shown as being rotatably mounted onperforated hollow shafts 79, the perforations being indicated at 7% inFIG. 14. This arrangement is such that the moisture-laden air blownthrough the felt into the interior of the drums 76 will be passedintoand through the interior of the hollow shafts 79 and discharged from thelater into any suitable collecting means disposed outside of the tank73. If desired, the ends of all of the shafts 79 may be connected into asingle chamber which may be maintained under a vacuum to assist insucking the moisture-laden air out of the drums 76. Preferably the drumsare arranged to rotate about their hollow shafts which remainstationary. However, the hollow shafts may be arranged to rotate withthe drums, if desired. Also in lieu of providing each of the drums 76with hollow perforated shafts, they may simply be provided with hollowtrunnions at their two ends, these being journaled in suitable bearings.

In FIG. 15 there is shown a still further embodiment of the invention.In this embodiment there is provided a pair of squeeze or press rolls 80and 81 through the nip of which the felt 27 is passed. Both rollers areperforated or of porous construction to permit the passage of air, waterand the like. They may be formed as regular steel drums, withperforations throughout their circumference and a suitable portion oftheir length equal to the width of the felt, or they may be formed fromribbons of fiber metal to provide a honeycomb construction. In thedrawing, the roll 80 is illustrated as being provided with perforations80a and the roll 81 is shown as provided with perforations 81a. Withinthe roll 80 there is mounted an elongated receptacle 83b which is heldstationary within the roll. It is provided with an air inlet 80c and anopen arcuate outer face conforming with the inner surface of the roll80. Suitable sealing means, of the general character explained above,should -be provided between the peripheral edges of the receptacle 89band the inner surface of the roll 80. In a similar manner the roll 81 isprovided with a receptacle 81b having an outlet 810 for the discharge ofair and water collected by the receptacle. It is preferably providedwith suitable sealing means around its periphery which engages the innersurface of the roll 81. The discharge of air and water from thereceptacle 81b may be under atmospheric pressure, but it is preferablydone under suction. The spacing of the rolls 80 and 81 may be madeadjustable so that as the felt passes through the nip the felt may besubjected to a desired amount of compression, preferably between 30% and50% of the initial thickness of the felt. Air introduced under pressureinto the receptacle 80b is forced through the openings 80a, through thefelt 27 and then through the openings 81a into the receptacle 811;. Thisarrangement makes possible the subjection of the felt to graduallyincreasing compression up to a predetermined maximum while the air underpressure is forced through the same to purge the water therefrom. As thefelt advances to the opposite side of the nip and outwardly beyond thesame it is released of its compression and restored to its originalthickness. During that portion of the arc in which the felt is subjectedto increased compression it is possible to keep the compressed felt in acondition in which it has a film or layer of water which prevents thefree passage of air through the felt. This enables the air to force thewater out of the felt with a piston-like action. In that region in whichthe felt is free to expand again, beyond the point of maximumcompression, it may no longer have an uninterrupted layer of water andthe air may move through it more freely. This increases somewhat thevolume of air needed, but it assists in further reducing the watercontent of the felt through entrainment and the like. If desired, theare over which the receptacles 80b and 81b extend may be such as toencompass the region only in which the felt is subjected to increasingcompression. In this event the forward or upstream walls of thereceptacles 80b and 81b may be made adjustable so that these walls willbe located in the region in which the rolls 80 and 81 just begin tocompress the felt, of whatever thickness it may be. This will serve todecrease the amount of air required to be introduced into the roll 80under the required pressure.

A plurality of squeeze or press rolls 80 and 81 may be provided inseries to act upon the felt successively, and thus increase the timeduring which air under pressure may be blown through the felt.

In the various forms of the invention described above, which involve theemployment of a supporting fabric, it will be understood that thepurging air will remove water not only from the felt but the supportingfabric as well. If it is found that the supporting fabric is notadequately purged of its water, but retains some which has been blowninto it from the felt, separate air purging devices of any of the typesdescribed above may be positioned in the path of movement of thesupporting fabric in the region where it is alone and not in contactwith the felt.

It will be clear from the foregoing that the employment of the presentinvention makes possible the great reduction in the water content of thefelt between the time it separates from the paper web until it isbrought back into contact with the latter. This in turn makes possiblethe removal of a greater amount of water from the paper web than ispossible by arrangements previously used or suggested. As a result ofthis the dryer portion of a paper machine may be reduced in size ascompared with that found necessary at the present time. Also theinvention makes possible the higher speed operation of the papermakingmachine that has long been sought.

In connection with the various embodiments of the invention, asdescribed above, with the exception of that shown in FIG. 15, it hasbeen found highly desirable to have the openings or passages in the areain which the water purging air is blown through the felt of suchcrosssectional area as to be more than 30% of the total area of theregion in which the purging action takes place. This leads to moreeffective and more speedy removal of the water from the felt than if thecross-sectional area of the openings is less in proportion to the totalarea of the purging region.

It Will be understood that various modifications of the invention, inaddition to the various forms herein described in some detail, may bemade within the scope of the invention.

What is claimed is:

1. Apparatus for drying successive portions of a continuously advancingpaper machine felt employed in a press section of the machine, in aregion between the point at which successive portions of the felt areseparated from the wet paper web being formed and the point at whichsaid portions are brought back into engagement vn'th another portion ofthe wet web, comprising:

(a) means having a discharge outlet for directing air undersuper-atmospheric pressure of at least 8 pounds per square inch throughthe successive portions of the felt;

(b) means for firmly retaining the successive portions of the feltagainst all portions of the periphery of said discharge outlet toprovide an effective seal again the discharge of air along the surfaceof the felt, said firmly retaining means including:

(1) narrow belts positioned to cooperate with the successive portions ofthe felt adjacent longitudinal edges thereof;

(2) means for advancing said belts at the speed of movement of the felt;and

(3) low friction creating and wear resistant elements extendingcompletely across the forward and rearward ends of said discharge outletand transversely of the felt;

(c) at least one porous supporting belt adapted to engage and cover onesurface of the felt in the region in which the latter is advanced acrosssaid discharge outlet so that the air blown through said outlet ispassed through both the felt and said supporting belt; said narrow belt,said means for advancing said belts, and said low friction creating andwear resistant elements being so constructed and arranged as to causesubstantially all of the voids in the successive portions of the felt tobe at least partially filled with water during at least a part of theirtravel along said discharge outlet.

2. Apparatus of the character set forth in claim 1 further includingmeans for carrying said porous supporting belt in a manner arranged toapply a substantial compressive force to the felt.

3. Apparatus of the character set forth in claim 1 further including:

(a) means for directing said supporting belt away from the felt at apoint beyond the region in which the said supporting belt is advancedwith the felt across said discharge outlet and for directing saidsupporting belt back into engagement with the felt at a point in advanceof the region, and

(b) means for removing liquid from said supporting belt at a pointbetween the separation of said supporting belt from the felt and thepoint where contact between said supporting belt and the felt is againrestored.

4. Apparatus of the character set forth in claim 3 wherein said liquidremoving means comprises means for directing high velocity air throughsaid supporting belt.

5. Apparatus for drying successive portions of a continuously advancingpaper machine felt employed in a press section of the machine, in aregion between the point at which successive portions of the felt areseparated from the wet paper web being formed and the point at whichsaid portions are brought back into engagement with another portion ofthe wet web, comprising:

(a) means having a discharge outlet for directing air undersuper-atmospheric pressure of at least 8 pounds per square inch throughthe successive portions of the felt, said means having a dimensionlengthwise of the movement of the felt sufficient to enable air to beblown through the felt for a period of time sufficient to reduce themoisture content of the felt to between 10 and 40% wet basis,

(b) means for firmly retaining the successive portions of the feltagainst all portions of the periphery of said discharge outlet toprovide an effective seal against the discharge of air along the surfaceof the felt, said firmly retaining means being so constructed andarranged as to cause substantially all of the voids in the successiveportions of the felt to be at least partially filled with water duringat least a part of their travel along said discharge outlet,

() a perforated drum rotatable at a peripheral speed equal to the speedof advance of the felt,

(d) means for delivering the felt to said perforated drum and forremoving the felt from said perforated drum in such a manner as to causethe felt to travel with said perforated drum over a major portion of thecircumference thereof,

(e) means for introducing air under pressure into the interior of saidperforated drum for discharge through the perforations therein andthrough the felt, and

(f) means surrounding a substantial portion of said perforated drum forcollecting water and air discharged from the felt.

6. Apparatus of the character set forth in claim further including aporous supporting member for the felt, said supporting membersurrounding the drum substantially throughout the arc in which the feltis engaged with the drum and holding the felt firmly against said drum.

7. Apparatus of the character set forth in claim 5 further includingshielding and sealing means for preventing any substantial escape of airfrom the interior of said drum without first passing through the felt.

8. A method of drying successive portions of a continuously advancingpaper machine felt leaving a pair of press rolls along with the paperWeb being formed in the course of operation of the machine as successiveportions of the felt travel from the point at which they leave the wetpaper web to the point at which they are again 5 brought into contactwith another portion of the wet web comprising the steps of:

(a) holding the felt firmly against a plurality of orifices bytemporarily applying a porous carrier to the surface of the feltopposite the orifices,

('b) advancing the felt and said porous carrier across said orifices,

(c) blowing air under substantial super-atmospheric pressure throughsaid plurality of orifices as the felt and said porous carrier areadvanced thereacross for a period of time suflicient to reduce the watercontent of the felt to between and 40% wet basis, substantially all ofsaid air being directed against one surface of the felt and passingthrough the felt and said porous carrier without any appreciable escapeof air laterally from the surface of the felt,

(d) directing high velocity air through successive portions of saidporous carrier as the successive portions of the said porous carrierpass through a region between the point at which they are moved awayfrom the felt, after having been passed with the felt across theorifices, and the point where the successive portions of the said porouscarrier are again returned into contact with the felt, said highvelocity air removing liquid from said porous carrier.

References Cited by the Examiner UNITED STATES PATENTS 4O DONALL H.SYLVESTER, Primary Examiner.

H. CAINE, Assistant Examiner.

8. A METHOD OF DRYING SUCCESSIVE PORTIONS OF A CONTINUOUSLY ADVANCINGPAPER MACHINE FELT LEAVING A PAIR OF PRESS ROLLS ALONG WITH THE PAPERWEB BEING FORMED IN THE COURSE OF OPERATION OF THE MACHINE AS SUCCESSIVEPORTIONS OF THE FELT TRAVEL FROM THE POINT AT WHICH THEY LEAVE THE WETPAPER WEB TO THE POINT AT WHICH THEY ARE AGAIN BROUGHT INTO CONTACT WITHANOTHER PORTION OF THE WET WEB COMPRISING THE STEPS OF: (A) HOLDING THEFELT FIRMLY AGAINST A PLURALITY OF ORIFICES BY TEMPORARILY APPLYING APOROUS CARRIER TO THE SURFACE OF THE FELT OPPOSITE THE ORIFICES, (B)ADVANCING THE FELT AND SAID POROUS CARRIER ACROSS SAID ORIFICES, (C)BLOWING AIR UNDER SUBSTANTIAL SUPER-ATMOSPHERIC PRESSURE THROUGH SAIDPLURALITY OF ORIFICES AS THE FELT AND SAID POROUS CARRIER ARE ADVANCEDTHEREACROSS FOR